Ορισμός και Σημασία του "one's luck is in"

What is the origin of the idiom "one's luck is in" and when to use it?

The phrase "one's luck is in" is an informal idiomatic expression that signifies a period of good fortune or a favorable streak. The origin of this phrase is rooted in the notion that someone's luck has improved or is currently on the upswing. It is often used to describe a situation in which things are going well for an individual, typically in a casual or conversational context.